1. Field of the Invention
The present invention relates to a spark arrestor and, more specifically, it relates to a spark arrestor which may be employed in combination with a torch used to process portions of a metal workpiece in the process of cutting, heating or welding the metal workpiece while focusing upon resisting undesired spreading of flames or sparks to adjacent people or material in order to minimize or eliminate the risk of employee burns and fires.
2. Description of the Prior Art
In connection with conventional railroad operations, it is periodically necessary to remove railroad rails which have become worn or otherwise deteriorated and are not serviceable with the degree of safety required. It is conventional to use a cutting torch to cut portions of the upper rail underlying the upper flange approximately every forty feet along the length of the rail.
When cutting rail, the rail is first measured with a measuring wheel 40 feet in length and marked with paint stick, and making a mark thereafter every 40 feet. Then the cutting torch is used to make the cuts. With the tip of the torch pointing straight down on top of the rail head, a cut is started and made directly across the shortest exit out of the other side of the rail head. The cut is made only through the head of the rail and starting into the web of the rail (directly under center of the head) approximately ¼ of an inch. Total length of this cut is less than 3 inches. It takes less than 15 seconds for an experienced torch man to make the cut.
If the rail is laying on its side, the person operating the cutting torch may choose to cut through ½ of the rail head side pointing up about an inch long and ½ through the base side pointing up (about 3 inches long) or may cut all the way across the base (about 6 inches long) or all the way across the head, whatever is allowed by the terrain. A cut will be made every 40 feet until the end is reached. All work is performed while using on track transportation, a high rail truck is used to haul the tools needed, and this truck may also be used to travel on railroad access roads to drive along side of the work when conditions are permitting.
The removal of the rail involves a high rail boom truck. This is a straight truck or a tractor trailer (semi) which hauls the rail and has a knuckle boom loader mounted on it to pick up the rail. The boom truck is a straight truck and cannot haul 40 foot rail. It, therefore, must be accompanied by a high rail cart. This cart has a 16-18 foot tow bar which allows it to be far enough from the truck for an overhang of approximately 8-10 feet. The overall picture would be that the cart is about 16 feet in length and an even length will hang over the front as what will hang over the rear of the cart (centered). This truck has remote control operation from the loader seat and can be driven from this seat while on the rail and working. The operator reaches down close to the cut on the rail and lifts approximately 10 to 18 inches until the rail snaps the rest of the way through from the torch cut, then sets it back on the ground and lets loose of it to reposition to load the rail on the cart.
Railroad ties are not replaced in this process. The ties are not fire resistant and are not treated to be fire resistant. They sometimes do catch fire. Sparks and flames may fly up into the tracks.
There is also a need for such a spark arrestor in connection with additional operations wherein a torch emitting flames is employed cut a metal workpiece, as by severing a portion from an elongated piece of the same or to cut openings or make other cuts of the same, or to preheat the workpiece which will be subjected to subsequent processing such as welding, for example.
While prior efforts have been made to deal with this serious problem of flames and sparks, to-date none have provided a successful, economically feasible, technically effective solution.
U.S. Pat. No. 2,911,038 discloses a flexible, self-supporting welding shield which is structured to be placed around the area of activity and resist sparks, flashes and hot particles. The structure includes an inner mesh 5, a pair of fabric elements 2,3 and support elements 10. Fastening rings 7 are provided to secure the elements in the desired position. The structure is not suitable for use in the present invention's environment, as there is no way of providing seals underlying the lower edge of the shield. As a result, sparks and flames could emerge therefrom. Also, there is no way of providing continuity of protection, as there is no position in which a rail could pass through the structure.
Japanese Abstract JP2001239269 discloses a spark shield sheet which is said to be freely bendable and consists of wire gauze 3 in combination with a flame resistant sheet 2 along with metal fittings 4. In the brief English language translation, it is stated that the flame resistant sheet may be folded into a box shape. While this might provide an enclosure of sorts, for reasons stated hereinbefore, it would not be suitable to solve the problem which the present invention has solved in respect of use of a flame torch to cut portions of a railroad rail which are to be removed.
U.S. Pat. No. 2,491,957 discloses a type of shield which is said to be transparent or translucent and is to be positioned over industrial equipment and secured in place by permanent magnets. While it does disclose the concept of shielding of sparks, it is in an industrial environment and provides a shield which would not be suitable for the problem solved by the present invention.
U.S. Pat. No. 5,854,461 discloses a welding shield adapted to reduce the amount of heat to which a welder's hand is exposed.
U.S. Pat. Nos. 4,622,781, 4,178,724 and 5,191,841 relate merely to mobile rail grinding equipment.
In spite of the foregoing disclosures, there remains a very real and substantial need for a spark arrestor capable of effectively resisting flames and sparks emerging from the shield during torch operations on a metal workpiece.